R&B singer Ne-Yo has taken legal action against R Kelly, claiming he was fired as the star's opening act on tour because fans and critics preferred him.
R Kelly (left) and Ne-Yo began their tour on 14 November
The musician is suing Kelly's tour promoters Rowe Entertainment for breach of contract and loss of earnings.
The star was to play 25 shows but claims he was fired after just two.
Promoters said the decision was made because a "final, fully executed contract" could not be obtained from Ne-Yo's agent.
Ne-Yo - whose real name is Shaffer Smith - and Compound Touring claim the star was to be paid $785,000 (£396,000) for 25 shows of Kelly's Double-Up tour and is still owed $735,000 (£371,000).
Legal papers stated: "An unknown representative of R Kelly urged Rowe to terminate Smith from the tour given the audience and critics' more favourable reaction to Smith than the reaction to R Kelly".
Compound Touring alleges it spent "substantial monies in preparation for the tour" and turned down other touring opportunities for Ne-Yo.
Kelly was not named as a defendant in the legal action, but the singer's representative said it was the promoter's decision to drop Ne-Yo from the tour.
"Anyone remotely familiar with R Kelly knows he is confident enough in his own abilities to be happy to share the stage with enormously talented people - the more talented, the better," they added.
Ne-Yo, who picked up two Mobo awards in September, scored a UK number one with So Sick in March 2006.